Physical exercise is characterized by an increase in oxygen consumption by the whole body. During oxygen metabolism, much of the oxygen consumed is bound to hydrogen during oxidative phosphorylation forming water. However, 4% to 5% of the oxygen consumed during respiration is not completely reduced to water, instead forming free radicals. Thus, the increase of oxygen consumption during an athletic competition generates a concomitant increase of free radical production and creates molecular cell damage such as peroxidation of lipids.
Many studies on animals and humans showed that polyphenols, vegetal secondary metabolites, are antioxidants and could decrease oxidative stress and the risk of associated diseases. Grape extracts rich in flavanols and particularly in procyanidine, such as Powergrape™ grape extract, are known to be good antioxidants in vitro and in vivo. Supplementation with grape extracts rich in flavanols and procyanidins has been shown to decrease oxidative stress induced by athletic competition in professional soccer players.
In one study aimed at determining if the grape extract (Powergrape™ grape extract, NATUREX) supplementation is able to decrease oxidative stress generated in professional athletes during a competition period, 200 mg of grape extract was administrated twice daily (400 mg/day) over 21 days to 7 professional soccer players. The experimental design was a longitudinal study without a placebo group. Plasma biomarkers of oxidative stress and antioxidant status were determined during a competition period, before (day 0) and after (day 21) grape extract supplementation. Blood parameters measured were Vitamin C, ascorbyl radical, Vitamin E, cholesterol, reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), glutathione peroxidase (GPx), thiol proteins, total hydrophilic antioxidant capacity, total lipophilic antioxidant capacity, and coenzyme Q10 (ubiquinone).
Results showed that the lipophilic antioxidant capacity was increased, so the total antioxidant capacity was also enhanced. The levels of glutathione (GSH) and oxidized glutathione (GSSH) were decreased, so the ratio of GSH/GSSH is normalized. The enzymes glutathione peroxidase (GPx) and superoxide dismutase (SOD) were decreased. An increase in coenzyme Q10 (ubiquinone) was observed. Vitamin C was strongly enhanced, by more than 60%, and its ratios with Vitamin E (Vitamin C/Vitamin E) and ascorbyl radical (Vitamin C/ascorbyl radical) were significantly increased. Results of this experiment are shown in Table 1 and FIG. 1.
TABLE 1Effects of grape extract (Powergrape ™ grape extract, NATUREX) onparameters of oxidative stress and antioxidant capacity in professional athletesin pre and post treatment (21 days).Pre-Post-treatmentReferencetreatment D0D21valuesMean +/− SDMean +/− SDUnityVitamin C 6.21-15.189.50 +/− 1.4515.16 +/− 3.91 μg/mLRadical ascorbyl0.28-0.440.40 +/− 0.070.51 +/− 0.10/VitC/Radical ascorbyl18.84-36.2024.32 +/− 5.32 30.59 +/− 7.88 /Vitamin E 8-1513.21 +/− 2.47 13.43 +/− 3.61 μg/mLCholesterol 1.4-2.002.06 +/− 0.472.03 +/− 0.38g/LVitE/cholesterol 4.4-7.006.44 +/− 1.136.62 +/− 1.15/VitC/VitE ratio>1.30.75 +/− 0.211.20 +/− 0.48/Reduced glutathion753-9581300.74 +/− 207.99 1010.56 +/− 164.27 μmol/L(GSH)Oxidized glutathion1.17-5.3227.03 +/− 21.143.34 +/− 1.41μmol/L(GSSG)GSH/GSSG ratio156-70593.94 +/− 79.94341.97 +/− 135.61/Superoxyde dismutase 785-15701755.43 +/− 367.01 1138.43 +/− 216.96 UI/g Hb(SOD)Gluhathion peroxidase30-5556.57 +/− 7.09 42.86 +/− 13.36UI/g Hb(GPx)Thiols proteins310.14-523.86418.19 +/− 15.41 445.55 +/− 52.55 μmol/LHydrophilic antioxidant138-334225.00 +/− 56.57 199.29 +/− 70.20 nmol eq aa/mLcapacityLipophilic antioxidant47-7459.64 +/− 6.15 67.83 +/− 4.49 nmol eqcapacityTrolox/mLCoenzyme Q100.4-1.20.48 +/− 0.130.94 +/− 0.29μg/mL(Ubiquinone)